package/rockchip-mali: new package

There is already a package adding Mali blobs for Sunxi Mali Utgard
GPUs. Many Rockchip SoCs feature a Mali Bifrost GPU and need specific
libraries provided under binary form with a non-GPL compliant license
by Rockchip. Package these libraries.

While the repository at https://github.com/rockchip-linux/libmali


supports many GPU variants, this package for now only supports the
Bifrost GPU blob. Support for other GPU blobs can be added later.

Signed-off-by: Maxime Chevallier <maxime.chevallier@bootlin.com>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
[Thomas:
- Rename to rockchip-mali, because it contains other blobs than
  Bifrost ones
- Add missing entry in DEVELOPERS file
- Change BR2_arm to BR2_ARM_EABIHF as only EABIhf blobs are provided
  for arm32
- Add BR2_TOOLCHAIN_HAS_THREADS inherited from libdrm.
- Expose as a libgbm provider.
- Drop the patch, which was not necessary.
- Rework the entire installation logic, to be much simpler.]
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>